xml serialization in ASP.NET WEB API

You can use the Serialize method to generate this xml from the model it self.

public string SerializeXml<T>(T config) 
        {
            XmlSerializer xsSubmit = new XmlSerializer(typeof(T));
            string xml = "";
            XmlWriterSettings settings = new XmlWriterSettings();
            settings.OmitXmlDeclaration = false;

            using (var sww = new StringWriter())
            {
                using (XmlWriter writer = XmlWriter.Create(sww, settings))
                {
                    xsSubmit.Serialize(writer, config);
                    xml = sww.ToString();
                }
            }

            return xml;
        }

This will return XML string , you need the model which is similar to your required XML. This is what i have created as model from your XML that you can change as per your requiment.

 [XmlRoot(ElementName = "affdatalist")]
    public class Affdatalist
    {
        [XmlElement(ElementName = "object1")]
        public string Object1 { get; set; }
        [XmlElement(ElementName = "object2")]
        public string Object2 { get; set; }
        [XmlElement(ElementName = "object3")]
        public string Object3 { get; set; }
    }

    [XmlRoot(ElementName = "personData")]
    public class PersonData
    {
        [XmlElement(ElementName = "affdatalist")]
        public Affdatalist Affdatalist { get; set; }
        [XmlElement(ElementName = "anotherObject1")]
        public string AnotherObject1 { get; set; }
        [XmlElement(ElementName = "anotherObject2")]
        public string AnotherObject2 { get; set; }
    }

    [XmlRoot(ElementName = "personDatas")]
    public class PersonDatas
    {
        [XmlElement(ElementName = "personData")]
        public PersonData PersonData { get; set; }
    }

You can use as sample below

PersonDatas data = new PersonDatas();
var xml = this.SerializeXml<PersonDatas>(data); // your model with data

If you want c# classes like this

using System;
using System.Xml.Serialization;
using System.Collections.Generic;
namespace namespace
{

    public class AffData {

        public string Property1 { get; set; }
    }




    public class AnotherObject1 {

        public string Property1 { get; set; }
    }


    public class AnotherObject2 {

        public string Property1 { get; set; }
    }


    public class PersonData {

        public List<AffData> AffDataList { get; set; }

        public AnotherObject1 AnotherObject1 { get; set; }

        public AnotherObject2 AnotherObject2 { get; set; }
    }

The below xml will work if you serialize List

<ArrayOfPersonData>
 <PersonData>
   <ArrayOfAffData>
     <AffData> 
<Property1>info</Property1>
 </AffData>
     <AffData> <Property1>info</Property1></AffData>
     <AffData> <Property1>info</Property1> </AffData>
   </ArrayOfAffData>
   <anotherObject1> <Property1>info</Property1> </anotherObject1>
   <anotherObject2> <Property1>info</Property1> </anotherObject2>
 </PersonData>
</ArrayOfPersonData>

 public static string ConvertToXml(object payload, string rootElement, bool addPrefixSuffix)
    {
        string json = JsonConvert.SerializeObject(payload);
        string elementName = "DummyRoot";
        if (addPrefixSuffix)
        {
            string prefix = "{" + elementName + ":";
            string postfix = "}";
            json = string.Concat(prefix, json, postfix);
        }
        var payloadXml = JsonConvert.DeserializeXNode(json, rootElement)?.ToString();
        if (addPrefixSuffix)
        {
            payloadXml = payloadXml.ToString().Replace("<" + elementName + ">", string.Empty);
            payloadXml = payloadXml.ToString().Replace("</" + elementName + ">", string.Empty);
        }
        return Regex.Replace(payloadXml, @"\s+", String.Empty);
    }

Use the above function like ConvertToXml(requeststring, "", false)... Here second parameter empty will returns your expected result.